DataTable: Provide screen reader compliant keyboard navigation

[Rene-Stoeckel]

Description

One can use the keyboard to navigate between the rows by using the up and down
arrow keys once the focus is moved from the table headers to the table body,
as demonstrated in the showcase here:

http://www.primefaces.org:8080/showcase/ui/data/datatable/lazy.xhtml

But this approach is insufficient in combination with screan readers (e.g. JAWS)
and thus is a serious accessibility limitation.

The problem is that the data tables are given the aria role "grid" so that
screen readers expect the "W3C Pattern Grid Interactive Tabular Data" (see below)
and expect the table to be navigated via the cursor keys from row to row and from cell to cell
similiar to excel, which is not implemented.
The focus currently stays on top on tbody instead of the "cells" so that the screen
reader does not read anything from the table content during navigation.

Describe the solution you would like

1. It would be nice to have an implementation of table navigation from row to row and cell to cell
   via cursor keys/ home / end / page up / page down according to the example in the WAI Pattern:
   https://www.w3.org/WAI/ARIA/apg/patterns/grid/examples/data-grids/

2. Instead of staying on tbody the keyboard focus would need to follow the cursor
   so that the screen readers will read the cells content.

Additional context

This is the heaviest finding in the acessibility assessment of our primefaces application.

Thank you for your great work on primefaces!

[melloware]

@Rene-Stoeckel i moved this ticket under sponsoring required: #11251

[melloware]

@Rene-Stoeckel i sent you an email.

[Rene-Stoeckel]

@Rene-Stoeckel i sent you an email.

Alright, thank you, I've answered it.

[melloware]

@Rene-Stoeckel another email sent do you not check your email regularly?

[melloware]

@Rene-Stoeckel please have your team test out this reproducer:
pf-11918.zip

Unzip and run mvn clean jetty:run and navigate to: http://localhost:8080/

Now cells are focuses and you can use Arrow keys and all of the keystrokes mentioned in the doc to navigate the cells and screen reader should read them.

[Rene-Stoeckel]

We just tested the reproducer (from 11918) with the screenreader and we can confirm that

1. the content of the table is correctly presented with the screenreader, just as expected.
2. cursor navigation is working as expected,

But there are things we noticed that still must be fixed here:

When a cell other than (1,1) is clicked with the mouse the cursor navigation is broken. The fokus travels to a different cell than expected and some cells can no longer be reached. E.g. select cell New York, navigate all way down and then all way up (cursor or page down/up) and the fokus will end up in cell 123.

[melloware]

Try this one:
pf-dt-accessibility.zip

[Rene-Stoeckel]

Thank you very much for the quick response. We tried this tester and the two issues are fixed. Screenreade and cursor navigation are as expeced.